Disclosed is a method for separating finely divided solids from a hydrocarbon slurry by using an additive that comprises a polymer and, optionally, an alkylbenzene sulfonic acid; and a composition of the additive thereof. The polymer is a polymer having (a) a polymeric backbone comprising polyol units and at least one unsaturated polycarboxylic unit, (b) acrylate units coordinated via unsaturated polycarboxylic units, and (c) oxyalkylated alkyl phenol units.